1. Field of the Invention
The present invention relates to a magnetic recording and reproduction apparatus, and in particular to a magnetic recording and reproduction apparatus having a machanism for moving a sub chassis relative to a main chassis.
2. Description of the Related Art
Recently, the reduction of size and the number of components and the simplification of the structure of magnetic recording and reproduction apparatuses has been actively pursued.
Hereinafter, a conventional magnetic recording and reproduction apparatus will be described.
One known conventional magnetic recording and reproduction apparatus is described in Japanese Laid-Open Publication No. 11-328773. A tape pull-out mechanism of the magnetic recording and reproduction apparatus is shown in FIGS. 18, 19, 24, 25, 26 and 27 of Japanese Laid-Open Publication No. 11-328773.
A cam gear 66 is driven by a motor (not shown) mounted on a main chassis 8 to pivot forward or backward. A boat driving arm 73 is driven by a driving pin 75 provided on the cam gear 66 to pivot about a pivoting center 74.
A gear 77 is provided at a tip of the boat driving arm 73, and is engaged with integral S loading gears 78, 79 and 80. The S loading gears 78, 79 and 80 are pivoted by the boat driving arm 73. An S loading arm 81 is pivoted by a pivoting force of the S loading gears 78, 79 and 80. An S boat 39 is moved from a cassette mounting position (FIG. 18) to a tape pull-out position (FIG. 19) by a pivoting force of the S loading arm 81. Thus, a magnetic tape is pulled out from a tape cassette. The S boat 39 is pressed to a positioning pin 141 provided on the main chassis 8. Thus, the position of the S boat 39 is determined.
In order to determine the position of the S boat 39 by pressing the S boat 39 to the positioning pin 141, a twisted coil spring (not shown) is provided between the S loading gear 79 and the S loading arm 81.
The magnetic tape is pulled out by a T boat 47 in substantially the same manner as by the S boat 39 as follows. A T loading gear 84 to engaged with the S loading gear 79, and is pivoted by a pivoting force of the S loading gear 79. A T loading arm 86 is pivoted by a pivoting force of the T loading gear 84. The T boat 47 is moved from the cassette mounting position to the tape pull-out position by a pivoting force of the T loading arm 86. Thus, the magnetic tape is pulled out from the tape cassette. The T boat 47 is pressed to a positioning pin 142 provided on the main chassis 8. Thus, the position of the T boat 47 is determined.
FIG. 10 shows a flow of forces in the tape pull-out mechanism of the conventional magnetic recording and reproduction apparatus described in the above-mentioned publication. A force generated by a motor is divided into two forces by the cam gear, one of which is further divided into two forces by the S loading gears 78, 79 and 80, and the other of which is further divided into two forces by a sub chassis. As can be appreciated, the flow of forces in the tape pull-out mechanism of the conventional magnetic recording and reproduction apparatus is quite complicated.
The conventional magnetic recording and reproduction apparatus has the following problems. Since the pivoting force of the cam gear 66 is conveyed to the S loading arm 81 and the T loading arm 86 via many components including the boat driving arm 73, the S loading gear 79, and the T loading gear 84, the tape pull-out mechanism requires a great number of components. Moreover, the flow of forces in the tape pull-out mechanism is quite complicated as described above, which further increases the number of required components and prevents reduction of the number of components. Since a plurality of arms are provided above and below the cam gear 66, the tape pull-out mechanism is inevitably thick and thus prevents weight reduction of the tape pull-out mechanism. A large range in which the boat driving arm 73 pivots also prevents size reduction of the tape pull-out mechanism.